Reduction in genome size has been associated not only with a parasitic lifestyle in
intracellular microparasites but also in some macroparasitic insects and nematodes.
We collected the available data on genome size for flatworms, annelids, nematodes
and arthropods, compared those with available data for the phylogenetically closest
free-living taxa and found evidence of smaller genome sizes for parasites in six of
nine comparisons. Our results suggest that despite great differences in evolutionary
history and life cycles, parasitism as a lifestyle promotes convergent genome size
reduction in macroparasites. We discuss factors that could be associated with small
genome size in parasites which require further exploration in the future.

The obligate intracellular protozoan parasite Toxoplasma gondii interferes with major
histocompatibility complex (MHC)-II antigen presentation to dampen host CD4(+) T cell
responses. While it is known that T. gondii inhibits MHC-II gene transcription and
expression in infected host cells, the mechanism of this host manipulation is unknown.
Here, we show that soluble parasite proteins inhibit IFNγ-induced expression of MHC-II
on the surface of the infected cell in a dose-dependent response that was abolished
by protease treatment. Subcellular fractionation of T. gondii tachyzoites revealed
that the MHC-II inhibitory activity co-partitioned with rhoptries (ROP) and/or dense
granules (GRA). However, parasite mutants deleted for single ROP or GRA genes (ROP1,
4/7, 14, 16 and 18 or GRA 2 - 9 and 12 knock-out strains) retained the ability to
inhibit expression of MHC-II. In addition, excreted/secreted antigens (ESA) released
by extracellular tachyzoites displayed immunomodulatory activity characterized by
an inhibition of MHC-II expression, and reduced expression and release of TNFα by
macrophages. Tandem MS analysis of parasite ESA generated a list of T. gondii secreted
proteins that may participate in MHC-II inhibition and the modulation of host immune
functions.

The major purpose of this study was to assess the association between the potential
long-term effects of previous schistosome infection and atherogenic dyslipidemia.
Among 1597 men aged ⩾45years who received health examinations and lived in previous
schistosomiasis-endemic regions of China, 465 patients with previous schistosome infection
were selected as study subjects, and 1132 subjects formed the control group. The risk
factors for cardiovascular disease were measured and compared between the previous
schistosome infection and control groups. The Atherogenic Index of Plasma, triglycerides,
waist circumference and body mass index were significantly lower in the previous schistosome
infection group than in the control group (all P values <0.001), whereas high-density
lipoprotein-cholesterol was significantly higher in the previous schistosome infection
group (P<0.001). In the Atherogenic Index of Plasma quartiles (Q1-Q4), the percentages
of subjects with previous schistosome infection were 55.89% (Q1), 25.44% (Q2), 16.33%
(Q3), and 18.8% (Q4), respectively (χ(2)=139.86, P<0.001). A logistic regression analysis
based on previous schistosome infection as the independent variable and Atherogenic
Index of Plasma as the dependent variable revealed that previous schistosome infection
was significantly negatively correlated with Atherogenic Index of Plasma (odds ratio=0.583,
95% confidence interval: 0.440-0.772, P<0.001) after adjustment for body mass index,
waist circumference, diastolic blood pressure and uric acid, suggesting that previous
schistosome infection is an independent factor associated with Atherogenic Index of
Plasma. The potential long-term effects of previous schistosome infection may reduce
the Atherogenic Index of Plasma in Chinese men. However, further studies are required
to investigate the protective human immune response against schistosome infections.
The development of a schistosomiasis vaccine may effectively prevent the development
and progression of atherosclerosis.

Gastro-allergic anisakiasis and Anisakis sensitisation associated chronic urticaria
are diseases which differ in their IgE and IgG4 responses against both crude extract
and specific allergens. Anisakis and Ascaris are closely related nematodes that usually
cause problems with specificity in immunodiagnostics. In this study we measured IgE
and IgG4 antibodies against Anisakis simplex sensu lato (s. l.) and Ascaris suum haemoglobins
in sera of 21 gastro-allergic anisakiasis and 23 chronic urticaria patients. We used
a capture ELISA with the anti-Anisakis haemoglobin monoclonal antibody 4E8g, which
also recognises Ascaris haemoglobin. In addition, we determined specific IgE and IgG4
to both nematodes by indirect ELISA and immunoblotting. Anti-A. simplex s. l. haemoglobin
IgE and IgG4 levels were higher in gastro-allergic anisakiasis than in chronic urticaria
patients (P=0.002 and 0.026, respectively). Surprisingly, no patient had detectable
IgE levels against A. suum haemoglobin. Finally, we carried out an in silico study
of the B-cell epitopes of both haemoglobin molecules. Five epitopes were predicted
in Anisakis pegreffii and four in A. suum haemoglobin. The epitope propensity values
of Anisakis haemoglobin in the equivalent IgE binding region of the allergenic haemoglobin
Chi t 1 from Chironomus thummi, were higher those of the Ascaris haemoglobin. In conclusion,
we describe A. simplex haemoglobin as a new major allergen (Ani s 13), being recognised
by a large number (64.3%) of sensitised patients and up to 80.9% in patients with
gastro-allergic anisakiasis. The presence of a specific epitope and the different
values of epitope propensity between Anisakis and Ascaris haemoglobin could explain
the lack of cross-reactivity between the two molecules. The absence of IgE reactivity
to Ascaris haemoglobin in Anisakis patients makes Anisakis haemoglobin (Ani s 13)
a potential candidate for developing more specific diagnosis tools.

ES-62 is an anti-inflammatory phosphorylcholine-containing glycoprotein secreted by
the filarial nematode Acanthocheilonema viteae. Accelerated atherosclerosis frequently
occurs in systemic lupus erythematosus, resulting in substantial cardiovascular morbidity
and mortality. We examined the effects of ES-62 in the gld.apoE(-/-) mouse model of
this condition. Treatment with ES-62 did not substantially modulate renal pathology
but caused decreased anti-nuclear autoantibody levels. Moreover, a striking 60% reduction
in aortic atherosclerotic lesions was observed, with an associated decrease in macrophages
and fibrosis. We believe that these latter findings constitute the first example of
a defined parasitic worm product with therapeutic potential in atherosclerosis: ES-62-based
drugs may represent a novel approach to control accelerated atherosclerosis in systemic
lupus erythematosus.

The relationship between the manifestations of tolerance (a host's ability to reduce
the impact of a given level of pathogens) and resistance (a host's ability to clear
pathogens) has been assumed to be an antagonistic one. Here we tested the hypothesis
that mice from strains more resistant to intestinal nematodes will experience reduced
tolerance compared with less resistant mice. Three inbred strains of mice were used:
C57BL/6 mice have been characterised as susceptible, whereas BALB/c and NIH mice have
been characterised as resistant to Heligmosomoides bakeri infection. Mice of each
strain were either parasitised with a single dose of 250 L3H. bakeri (n=10) in water
or were sham-infected with water (n=10). Body weight, food intake and worm egg output
were recorded regularly throughout the experiment. Forty-two days p.i. mice were euthanised
and organ weights, eggs in colon and worm counts were determined. C57BL/6 mice showed
significantly greater worm egg output (P<0.001), eggs in colon (P<0.05) and female
worm fecundity (P<0.05) compared with NIH and BALB/c mice. Parasitised BALB/c mice
grew more whilst parasitised C57BL/6 mice grew less than their sham-infected counterparts
during the first 2weeks post-challenge (P=0.05). Parasitism significantly increased
liver, spleen, small intestine and caecum weights (P<0.001) but reduced carcass weight
(P<0.01). Average daily weight gain and worm numbers were positively correlated in
NIH mice (P=0.05); however, the relationship was reversed when carcass weight was
used as a measure for tolerance. BALB/c mice did not appear to suffer from the consequences
of parasitism, with carcass weight similar in all animals. Our hypothesis that strains
more resistant to the H. bakeri infection are less tolerant compared with less resistant
strains is rejected, as the two resistant strains showed variable tolerance. Thus,
tolerance and resistance to an intestinal nematode infection are not always mutually
exclusive.

Myxosporea (Myxozoa), a group of parasitic Cnidaria, use mostly bony fishes (Teleostei)
as intermediate hosts; however, they can also parasitize other vertebrates such as
cartilaginous fish (Chondrichthyes). Molecular data of myxosporeans from sharks and
rays (Elasmobranchii) revealed these parasites to be one of the most basal representatives
in the myxosporean phylogenetic tree, suggesting their ancient evolutionary history.
A new myxosporean species, Bipteria vetusta n. sp., was found in the gall bladder
of rabbit fish, Chimaera monstrosa (Holocephali; Chondrichthyes), and ssrDNA-based
phylogeny revealed its basal position within the marine myxosporean lineage. Molecular
dating based on ssrDNA analysis suggested the origin of a stem lineage leading to
the marine myxosporean lineage at the time of the origin of Chondrichthyes in the
Silurian era. The two common lineages of Myxozoa, Myxosporea and Malacosporea, were
estimated to have split from their common ancestor in the Cambrian era. Tracing the
history of evolution of the "vertebrate host type" character in the context of molecular
dating showed that cartilaginous fish represented an ancestral state for all myxosporeans.
Teleosts were very likely subsequently parasitized by myxozoans four times, independently.
Myxosporean radiation and diversification appear to correlate with intermediate host
evolution. The first intermediate hosts of myxosporeans were cartilaginous fish. When
bony fish evolved and radiated, myxosporeans switched and adapted to bony fish, and
subsequently greatly diversified in this new host niche. We believe that the present
study is the first attempt at molecular dating of myxozoan evolution based on an old
myxosporean species - a living myxosporean fossil.

Echinococcosis is a worldwide zoonosis of great public health concern, considered
a neglected disease by the World Health Organisation. The cestode parasites Echinococcus
granulosus sensu lato (s. l.) and Echinococcus multilocularis are the main aetiological
agents. In the intermediate host, these parasites display particular developmental
traits that lead to different patterns of disease progression. In an attempt to understand
the causes of these differences, we focused on the analysis of microRNAs (miRNAs),
small non-coding regulatory RNAs with major roles in development of animals and plants.
In this work, we analysed the small RNA expression pattern of the metacestode, the
stage of sanitary relevance, and provide a detailed description of Echinococcus miRNAs.
Using high-throughput small RNA sequencing, we believe that we have carried out the
first experimental identification of miRNAs in E. multilocularis and have expanded
the Echinococcus miRNA catalogue to 38 miRNA genes, including one miRNA only present
in E. granulosus s. l. Our findings show that although both species share the top
five highest expressed miRNAs, 13 are differentially expressed, which could be related
to developmental differences. We also provide evidence that uridylation is the main
miRNA processing mechanism in Echinococcus spp. These results provide detailed information
on Echinococcus miRNAs, which is the first step in understanding their role in parasite
biology and disease establishment and/or progression, and their future potential use
as drug or diagnostic targets.

Equine internal parasites, mostly cyathostomins, affect both horse welfare and performance. The appearance of anthelmintic-resistant parasites creates a pressing need for optimising drenching schemes. This optimization may be achieved by identifying genetic markers associated with host susceptibility to infection and then to drench carriers of these markers. The aim of our study was to characterise the genetics of horse resistance to strongyle infection by estimating heritability of this trait in an Arabian pure blood population. A population of 789 Arabian pure blood horses from the Michałów stud farm, Poland were measured for strongyle egg excretion twice a year, over 8years. Low repeatability values were found for faecal egg counts. Our analyses showed that less than 10% of the observed variation for strongyle faecal egg counts in this population had a genetic origin. However, additional analyses highlighted an age-dependent increase in heritability which was 0.04 (±0.02) in young horses (up to 3years of age) but 0.21 (±0.04) in older ones. These results suggest that a significant part of the inter-individual variation has a genetic origin. This paves the way to a genomic dissection of horse-nematode interactions which might provide predictive markers of susceptibility, allowing individualised drenching schemes.

Assessment of the genetic variability and population structure of Trypanosoma rangeli,
a non-pathogenic American trypanosome, was carried out through microsatellite and
single-nucleotide polymorphism analyses. Two approaches were used for microsatellite
typing: data mining in expressed sequence tag /open reading frame expressed sequence
tags libraries and PCR-based Isolation of Microsatellite Arrays from genomic libraries.
All microsatellites found were evaluated for their abundance, frequency and usefulness
as markers. Genotyping of T. rangeli strains and clones was performed for 18 loci
amplified by PCR from expressed sequence tag/open reading frame expressed sequence
tags libraries. The presence of single-nucleotide polymorphisms in the nuclear, multi-copy,
spliced leader gene was assessed in 18 T. rangeli strains, and the results show that
T. rangeli has a predominantly clonal population structure, allowing a robust phylogenetic
analysis. Microsatellite typing revealed a subdivision of the KP1(-) genetic group,
which may be influenced by geographical location and/or by the co-evolution of parasite
and vectors occurring within the same geographical areas. The hypothesis of parasite-vector
co-evolution was corroborated by single-nucleotide polymorphism analysis of the spliced
leader gene. Taken together, the results suggest three T. rangeli groups: (i) the
T. rangeli Amazonian group; (ii) the T. rangeli KP1(-) group; and (iii) the T. rangeli
KP1(+) group. The latter two groups possibly evolved from the Amazonian group to produce
KP1(+) and KP1(-) strains.